1. Field of the Invention
This invention relates broadly to dental implants. More particularly, this invention relates to a device for removing maxillary bone to access the subantral membrane of the maxillary sinus, dissecting and elevating the subantral membrane, and injecting a filler under the subantral membrane for osseous regeneration to increase the bony support structure therein in preparation for receiving a dental implant.
2. State of the Art
Dental implants have been used in dentistry for about twenty years. They offer a tremendous benefit to patients by allowing for the replacement of missing teeth. The success of a dental implant is based on a variety of factors, including surgical technique, the health of the patient, operator skill, and, to a significant extent, the presence of sufficient bone for the placement and integration of the dental implant. To that end, dental implants are commonly used in the anterior lower jaw as this region provides sufficient bone quantity, quality, and strength to support and hold the dental implant. However, the replacement of the maxillary teeth has presented a considerable challenge because after the loss of maxillary teeth, the quality and quantity of the remaining supporting bone may be insufficient to properly and reliably support the dental implant.
More particularly, the maxillary complex is a three-dimensional bone structure composed of alveolar bone and basal bone. The maxillary teeth, and more specifically the teeth roots, are imbedded in the alveolar bone. The top of the maxillary complex forms the floor of the maxillary sinus and is covered by a thin diaphanous membrane known as the subantral or Schneiderian membrane (referred to herein as the “subantral membrane”). Once a tooth is removed from the maxillary complex, the surrounding alveolar bone is frequently resorbed because of the lack of physical stimulation and support of the teeth. This leads to a loss of bone mass and a corresponding reduction in the effective height and thickness of the bone of the maxillary complex, which if not remedied limits the potential use of the dental implant.
To overcome the deficiency of insufficient vertical bone mass of the maxillary complex, several surgical techniques have been developed to increase available bone mass for the placement of dental implants. These techniques augment the bone deficient region with a filler or regenerative material made of natural and/or artificial (synthetic) materials (collectively, ‘bone graft material’). Such material is placed on the roof of the maxillary structure under the subantral membrane so that it does not interfere with the function of the maxillary sinus. Collectively, these procedures are known within the dental profession as “sinus elevation procedures” with the goal of increasing the vertical height available for placement of dental implants. What makes these techniques unique from other techniques, such as distraction osteogenesis, is that the bone is increased within a body cavity, i.e., the maxillary sinus cavity.
Bone augmentation of the maxillary sinus requires careful bone removal and delicate dissection of the subantral membrane from the floor of the sinus. If the membrane is not properly dissected from the bone, bone augmentation may not occur, or may not be sufficient. Unintentional perforation of the subantral membrane may also lead to undesirable short and long-term consequences. If the perforation is large, such as, for example, several millimeters in diameter, the surgeon must either abort the procedure or use some means of removing or containing the bone graft material on the floor of the sinus to encourage new bone growth. Typically, a collagen membrane patch is used to repair the perforation and contain the bone graft material on the floor of the sinus. A lack of integrity of the membrane can also lead to the migration of bone graft materials leading to long-term chronic infections. Therefore, the maintenance of membrane integrity is of utmost importance during the elevation of the membrane to allow placement of bone graft materials with a goal of increasing bone mass in the maxilla.
A commonplace sinus elevation procedure requires a window into the maxillary sinus from a lateral and superior approach to the floor of the sinus. Great care must be taken during the entry to the sinus as it is critical not to perforate the subantral membrane that lines the sinus cavity. Most patients and dental surgeons acknowledge that entrance into the maxillary sinus utilizing a lateral window approach (also known as the Caldwell-Luc procedure) is an invasive procedure. This technique is fraught with many risks and complications because of the limitations of healing potential in the maxillary sinus. In spite of these risks many patients undergo this procedure because of the strong desire to replace missing maxillary teeth with dental implants.
An alternative procedure described by Dr. R. B. Summers approaches the maxillary sinus from the alveolar ridge utilizing solid cylindrical osteotomes. It is a more conservative approach and is less invasive. The technique vertically lifts the subantral membrane from the floor of the maxillary sinus via an infracture of the bony floor. The infracture can be performed using solid cylindrical osteotomes with specific diameters that are vertically advanced toward the maxillary sinus producing a mechanical lifting action on the membrane. Bone graft material is then placed into this space for bone augmentation. The bone graft materials are actually used to raise the subantral membrane. While this technique is safer than the lateral window approach, an overzealous use of an osteotome during the procedure can result in the perforation of the subantral membrane with the disadvantages discussed above.
U.S. Patent Pub. No. 2006/0084034 to Hochman discloses a method and apparatus for providing implants in the upper jaw of a person. The apparatus includes one or more sleeves having various lengths and diameters, each preferably including a tip for cutting a hole into the maxillary bone underneath the subantral membrane. The sleeve is hollow to allow fluid (gas, air, powder, paste, gel, or liquid) to be inserted under the membrane to cause it to lift from the sinus floor.
U.S. Patent Pub. No. 2006/0172255 to Hochman discloses a surgical tool having a fluid communication passageway that allows a fluid to be pumped into the tool at a defined pressure to displace the sinus membrane without compromising or tearing the membrane, thereby pushing the sinus membrane in an upward direction and creating a newly formed cavity space. The fluid passageway connects with radially extending holes through the shaft of the tool to allow fluid to pass therethrough.
In the prior art techniques discussed above, advancing a bone cutter through the maxillary bone with insufficient control or feedback and/or injecting bone graft materials in an axial direction under the subantral membrane after such uncontrolled cutting and lifting may result in tearing or ripping of the subantral membrane. Overcoming these previous limitations in the technique of sinus elevation will reduce infection, bleeding, swelling, pain, suffering and failure when using dental implants in the maxillary sinus.